<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>测试选择器</title>
    <style>
        .red {
            width: 100px;
            height: 100px;
            background-color: red;
        }
        
        .blue {
            width: 100px;
            height: 100px;
            background-color: blue;
        }
        
        #idxzq {
            font-size: 50px;
        }
    </style>
</head>

<body>
    <div class="red">红色</div>
    <div class="blue">蓝色</div>
    <div class="red">红色</div>

    <div id="idxzq">id选择器的使用</div>



</body>

</html>